PHPBuilder.com has posted the next part of their "Using XML" series - this time with a focus on SOAP and WSDL.

In the previous article in this series I demonstrated how XML is used to make remote procedure calls with XML-RPC in PHP. This article will focus on SOAP and WSDL (both of which use XML as their underlaying method of describing data) and demonstrate how a PHP script can act as a SOAP client and auto-magically discover detailed information about a web service.

They start with an overview of what SOAP is and how a simple SOAP message is structured. They also expand on that one step further with an example of a remote procedure call in a SOAP message.

Since the foundations are in place, they zip right along to the use of SOAP in your PHP 5 installation (one of the easiest methods). They help you create the SOAP client, generate the PHP code automatically from the remote WSDL, and utilize a proxy class to handle the connection.

With these scripts, they provide two examples of how to put them to work - one requests books on the topics of "php5" and "oop" from Amazon's web service and the other works with Google's API to "race" the results of certain search terms.